1. Field of the Invention
This invention relates to sintered magnets for use in magnetic sensors and to magnetic sensors.
2. Description of the Related Art
Conventionally, there have been used ring magnets in which a metallic pin is mounted with the aid of an adhesive in order to control the magnetic field. Although the presence of a pin in the bore of a ring magnet makes it possible to control the magnetic field, the interposition of an adhesive between the ring magnet and the metallic pin requires troublesome operations, and an uneven distribution of the adhesive is very likely to cause variations in bond strength. Moreover, a recent tendency is to use such ring magnets frequently at high temperatures. Higher temperatures cause a reduction in bond strength, resulting in a lack of thermal resistance.
Furthermore, the use of adhesives such as epoxy and phenolic adhesives enables a pin to be mounted in a magnet. However, a reduction in bond strength has been found to occur in organic solvents.
The present invention provides magnets in which the bond strength of a metallic pin within the magnet is high especially at high temperatures, the magnets scarcely undergoes deterioration by solvents, and the process steps for the production of the magnets can be simplified and hence bring about an improvement in productivity.
In view of the above-described problems, the present invention comprises a magnet made by mounting a metallic pin therein without using an adhesive. That is, the above-described problems can be solved by sintering the magnet and the metallic pin at the same time.
According to the present invention, the metallic pin inserted in the magnet has high thermal resistance and high bond strength, and the sign of the magnetic field can be changed to provide a highly sensitive magnetic sensor.